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Tue 29 Jul 2008 04:00 AM

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Comfortably clad

With energy efficiency and user comfort at the forefront of FM concerns, glass cladding in the Middle East needs to be reconsidered.

With energy efficiency and user comfort at the forefront of FM concerns, glass cladding in the Middle East needs to be reconsidered.

Architects generally agree that façade materials must be carefully chosen for their durability, aesthetic appeal and cultural suitability. As cladding provides viewers their first impressions of a building, architects need it to look the part.

"Choosing the right façade for a structure is vital," says Janus Rostock, senior designer for Atkins. "The façade reflects what the rest of the building is like. In the Middle East, traditionally, a façade has been very much just a skin to be clad onto a structure-a mask, so to speak-which does not express what is on the inside."

Facilities managers (FMs), on the other hand, need a building's cladding to act the part. To continue the metaphor, FMs need the "mask" to reflect the personality of the building, but more importantly, to cover, protect and safeguard its users.

Is it smart to build glass buildings in the middle of the desert? It is if you can harness the sun and use it to help with electricity costs. - Arthur Millwood, Emirates Glass

FMs need it to achieve environmental standards, perform well in myriad climates and ensure both visual and physical comfort to inhabitants. From an FM perspective, if a building doesn't safeguard the comfort of its users, it hasn't done its job, and frankly, neither has the FM.

Especially in Dubai-the world's fastest developing city; one of the world's richest cities; the commercial icon of the Middle East-what is perceived as cutting-edge or avant-garde is generally preferred to that which is more practical, and often, that which is more environmentally friendly.

Take, for example, the use of transparent glass. Architects love it because even the mundane functions of those inside provides a diverse and ever-changing façade for viewers. But in the scorching heat of the Middle East, that transparent glass fails to keep users cool without an excessive load on the building's cooling system.

"Architects want transparency. It's fashionable right now. They want to see the people, the furniture and everything that's happening in the building," says Arthur Millwood, technical manager of Emirates Glass. "But, with the amount of sunlight in the UAE, there will always be a problem with too much light. More transparency means higher heat gain, higher heat gain means less energy efficiency."

As Rostock points out, Dubai's economic abundance is attracting signature architects and top-quality FMs and neither they, nor their financially flamboyant clients, will be satisfied with a building that does anything short of dance, sing and sparkle.

But, while aesthetic and structural considerations are usually addressed by a combination of architects and engineers during conceptual design, FMs rate a building's success or failure on its ability to achieve performance and comfort standards. Put simply, FMs need a buildigy to put up or shut up. All too often, when those standards go unmet and that building doesn't put up, improper cladding is the usual suspect.

A case study

Millwood offers the Burj Dubai as an example of a building whose architects used reflective glass intelligently to keep its inhabitants cool and the sun out. Whereas BurJuman-Bur Dubai's massive high-end shopping mall and commercial centre-on the other hand, "uses a type of glass that has 50% light transmission so its inhabitants need to keep their blinds shut most of the time."

When keeping their blinds shut, inhabitants can effectively keep the sun out, but then the benefits of choosing glass cladding are lost.

According to Millwood, because Burj Dubai has achieved such worldwide recognition, it has the potential to single-handedly quell the use of transparent glass and actually point the industry back in the direction of reflective glass façades.

A case for efficiency

It's true that a glass façade can provide a building with a rainbow of external options in terms of colour, design and scope, but there is more to the argument than just aesthetics.One reason for choosing a glass façade is the technical advantage of keeping heat out and daylight in. Unglazed, transparent glass, by nature, allows direct sunlight in, which increases the amount of energy needed to keep a building cool and thereby, decreases its energy efficiency.

Increased thermal bridging combined with the harsh climate in the Middle East creates higher inside temperatures. After extended periods of exposure, these temperatures will significantly increase operational costs and thus, reduce a building's life-cycle.

"With the region's ambient temperatures and extremes in humidity levels there is a necessity for the system designers to be aware of the physics of a building façade," says Nael Afieh, director of Schüco International KG. "Façade physics in the Middle East...are opposite to those applied in more temperate climates...it is paramount to ensure that humidity never passes the water vapour line."

Glass is not great as a façade material, and if you look at traditional buildings in this region, you won’t see a lot of windows. - – Nick Lander, Atkins

Afieh's rationale being, that if the façade's water vapour line is exceeded, condensation occurs inside the façade and small particles of heat are passed through the water into the room.

Glass remains the region's most popular façade material but sceptics cite heightening solar gain and increasing temperatures as reasons to move away from the material. Nick Lander, regional head of sustainability for Atkins Middle East & India, ranks non-insulated materials-including glass-among the worst possible façade choices for the region.

"Glass is not great as a façade material, and if you look at traditional buildings in this region, you won't see a lot of windows," says Lander.

So, while architects and clients specify glass in ever-increasing amounts, FMs face the challenge of trying to make buildings clad with an inherently inefficient-not to mention regionally inappropriate-material, perform better and consume less energy.

"There are many factors to consider when choosing glass for a façade including aesthetics, cost, technical feasibility, life expectancy of the building, maintenance and, of course, getting it through planning permission," says Matthew Fan, senior architect for Kerr Blyth Associates.

The future of glass in the Middle East as it relates to fm

In Dubai, glass remains an incredibly popular material for both internal and external applications but those in the industry feel a change in the winds.

Despite the fanfare surrounding the Emirates LEED measurement tool and Abu Dhabi's Estidama New Building (ENB) tool, Bahrain, is still years ahead of Dubai in terms of legislating material use.

Bahrain is the Middle East leader in legislation that curbs the use of transparent glass in building projects. In Bahrain, the reflectivity levels and shading coefficients that can be used on glass are strictly enforced to reduce cooling costs and increase the overall life-cycle of buildings.

"The Emirates Green Building Council has drawn up a Dubai standard [for using glass with low reflectivity], which could become the federal standard in the UAE," says Millwood. "Bahrain is much stricter, but Dubai will move toward Bahrain."

It would seem that if, indeed, glass is the future of façades in the UAE, it will serve architects, developers and FMs- when allowed into the planning phase-very well to carefully consider the type of glass they use.

Until that day, however, architects will continue advocating transparent glass because it looks ultra-contemporary and developers will continue pushing for futuristic developments that promise high ROIs.

Meanwhile, after the designers, builders and investors are long gone, FMs will continue struggling between minimising cooling loads and operational costs and maximising comfort and overall life-cycles.

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